高比表面钛铌复合氧化物在气相Beckmann重排反应中的催化应用

Catalytic Application of Titanoniobium Composite Oxides with a High Specific Surface Area in the Vapor-Phase Beckmann Rearrangement

以K2CO3、Nb2O5和TiO2为原料，经高温固相反应制得KTiNbO5，进一步与HCl溶液反应后得到HTiNbO5。HTiNbO5经用长链有机胺预支撑，再与含Ti（IV）聚合阳离子溶液反应，所得产物在空气气氛中焙烧后制备出高比表面钛铌复合氧化物。它是一类多孔材料，其BRT比表面积达80～100m^2·g^-1。测试了该复合氧化物以及在该复合氧化物上负载B2O3后所得担载型催化剂在环己酮肟气相贝克曼重排反应中的催化性能。当B2O3负载量为7．31％（质量分数）时，环己酮肟转化率（～100％）在4．5h内无明显改变，反应进行6h后，转化率仍高于85％；己内酰胺选择性接近或超过90％且在整个反应过程中基本不变。

KTiNbO5 was synthesized by heating a stoichiometric mixture of K2CO3, La2O3, and Nb2O5, and HTiNbO5 was obtained by ion exchange of KTiNbO5 in HCl solution. HTiNbO5 was pre-expanded by longchain alkylamine, then reacting with a solution containing Ti （Ⅳ） polycations, followed by calcining the obtained precursor in air, two titanoniobium composite oxides （designated as HTNO） with a high specific surface area were prepared. The products were porous materials, and their BET surface areas were 80 ～ 100 m^2·g^-1. The vapor phase Beckmann rearrangement reaction of cyclohexanone oxime was studied with HTNO and B2O3/HTNO as catalysts. The B2O3/HTNO catalyst with B2O3 loading of 7.31 wt % exhibited 100% conversion of the oxime with ε-caprolactam selectivity near or beyond 90 %. The conversion was no significant change within 4.5 h and still higher than 85 % after 6 h.